/*********************************************************************
 * Software License Agreement (BSD License)
 *
 *  Copyright (C) 2010-2012 Ken Tossell
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above
 *     copyright notice, this list of conditions and the following
 *     disclaimer in the documentation and/or other materials provided
 *     with the distribution.
 *   * Neither the name of the author nor other contributors may be
 *     used to endorse or promote products derived from this software
 *     without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 *  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 *  COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 *  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 *  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 *  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 *  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 *  ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *  POSSIBILITY OF SUCH DAMAGE.
 *********************************************************************/
/**
 * @defgroup device Device handling and enumeration
 * @brief Support for finding, inspecting and opening UVC devices
 */

#include "Log.h"
#include "libuvc/libuvc.h"
#include "libuvc/libuvc_internal.h"

int uvc_already_open(uvc_context_t *ctx, struct libusb_device *usb_dev);
void uvc_free_devh(uvc_device_handle_t *devh);

uvc_error_t uvc_get_device_info(uvc_device_handle_t *devh, uvc_device_info_t **info);
void uvc_free_device_info(uvc_device_info_t *info);

uvc_error_t uvc_scan_control(uvc_device_handle_t *devh, uvc_device_info_t *info);
uvc_error_t uvc_parse_vc(uvc_device_t *dev, uvc_device_info_t *info, const unsigned char *block, size_t block_size);
uvc_error_t uvc_parse_vc_selector_unit(uvc_device_t *dev, uvc_device_info_t *info, const unsigned char *block,
                                       size_t block_size);
uvc_error_t uvc_parse_vc_extension_unit(uvc_device_t *dev, uvc_device_info_t *info, const unsigned char *block,
                                        size_t block_size);
uvc_error_t uvc_parse_vc_header(uvc_device_t *dev, uvc_device_info_t *info, const unsigned char *block,
                                size_t block_size);
uvc_error_t uvc_parse_vc_input_terminal(uvc_device_t *dev, uvc_device_info_t *info, const unsigned char *block,
                                        size_t block_size);
uvc_error_t uvc_parse_vc_processing_unit(uvc_device_t *dev, uvc_device_info_t *info, const unsigned char *block,
                                         size_t block_size);

uvc_error_t uvc_scan_streaming(uvc_device_t *dev, uvc_device_info_t *info, int interface_idx);
uvc_error_t uvc_parse_vs(uvc_device_t *dev, uvc_device_info_t *info, uvc_streaming_interface_t *stream_if,
                         const unsigned char *block, size_t block_size);
uvc_error_t uvc_parse_vs_format_uncompressed(uvc_streaming_interface_t *stream_if, const unsigned char *block,
                                             size_t block_size);
uvc_error_t uvc_parse_vs_format_mjpeg(uvc_streaming_interface_t *stream_if, const unsigned char *block,
                                      size_t block_size);
uvc_error_t uvc_parse_vs_frame_uncompressed(uvc_streaming_interface_t *stream_if, const unsigned char *block,
                                            size_t block_size);
uvc_error_t uvc_parse_vs_frame_format(uvc_streaming_interface_t *stream_if, const unsigned char *block,
                                      size_t block_size);
uvc_error_t uvc_parse_vs_frame_frame(uvc_streaming_interface_t *stream_if, const unsigned char *block,
                                     size_t block_size);
uvc_error_t uvc_parse_vs_input_header(uvc_streaming_interface_t *stream_if, const unsigned char *block,
                                      size_t block_size);

void LIBUSB_CALL _uvc_status_callback(struct libusb_transfer *transfer);

/** @internal
 * @brief Test whether the specified USB device has been opened as a UVC device
 * @ingroup device
 *
 * @param ctx Context in which to search for the UVC device
 * @param usb_dev USB device to find
 * @return true if the device is open in this context
 */
int uvc_already_open(uvc_context_t *ctx, struct libusb_device *usb_dev) {
    uvc_device_handle_t *devh;

    DL_FOREACH(ctx->open_devices, devh) {
        if (usb_dev == devh->dev->usb_dev)
            return 1;
    }

    return 0;
}

/** @brief Finds a camera identified by vendor, product and/or serial number
 * @ingroup device
 *
 * @param[in] ctx UVC context in which to search for the camera
 * @param[out] dev Reference to the camera, or NULL if not found
 * @param[in] vid Vendor ID number, optional
 * @param[in] pid Product ID number, optional
 * @param[in] sn Serial number or NULL
 * @return Error finding device or UVC_SUCCESS
 */
uvc_error_t uvc_find_device(uvc_context_t *ctx, uvc_device_t **dev, int vid, int pid, const char *sn) {
    uvc_error_t ret = UVC_SUCCESS;

    uvc_device_t **list;
    uvc_device_t *test_dev;
    int dev_idx;
    int found_dev;

    UVC_ENTER();

    ret = uvc_get_device_list(ctx, &list);

    if (ret != UVC_SUCCESS) {
        UVC_EXIT(ret);
        return ret;
    }

    dev_idx = 0;
    found_dev = 0;

    while (!found_dev && (test_dev = list[dev_idx++]) != NULL) {
        uvc_device_descriptor_t *desc;

        if (uvc_get_device_descriptor(test_dev, &desc) != UVC_SUCCESS)
            continue;

        if ((!vid || desc->idVendor == vid) && (!pid || desc->idProduct == pid) &&
            (!sn || (desc->serialNumber && !strcmp(desc->serialNumber, sn))))
            found_dev = 1;

        uvc_free_device_descriptor(desc);
    }

    if (found_dev)
        uvc_ref_device(test_dev);

    uvc_free_device_list(list, 1);

    if (found_dev) {
        *dev = test_dev;
        UVC_EXIT(UVC_SUCCESS);
        return UVC_SUCCESS;
    } else {
        UVC_EXIT(UVC_ERROR_NO_DEVICE);
        return UVC_ERROR_NO_DEVICE;
    }
}

uvc_error_t uvc_find_device_address(uvc_context_t *ctx, uvc_device_t **dev, int vId, int pId, int busNum,
                                    int devAddress) {
    libusb_device **list;
    ssize_t count = libusb_get_device_list(ctx->usb_ctx, &list);
    if (count < 0) {
        return UVC_ERROR_NO_DEVICE;
    }
    libusb_device *found = NULL;
    struct libusb_device_descriptor usb_desc;
    for (ssize_t i = 0; i < count; i++) {
        // 获取当前设备的总线号和设备地址
        libusb_device *usbDevice = list[i];
        if (libusb_get_device_descriptor(usbDevice, &usb_desc) != 0) {
            continue;
        }
        if (usb_desc.idVendor != vId || usb_desc.idProduct != pId) {
            continue;
        }
        uint8_t currentBusNum = libusb_get_bus_number(usbDevice);
        uint8_t currentDevAddress = libusb_get_device_address(usbDevice);
        LOG_D("设备的总线号和设备地址:%{public}d-%{public}d", currentBusNum, currentDevAddress);
        if (currentBusNum == busNum && currentDevAddress == devAddress) {
            found = list[i];
            break;
        }
    }
    // 释放设备列表（不释放找到的设备，因为引用计数已增加）
    libusb_free_device_list(list, 1);
    if (!found) {
        return UVC_ERROR_NO_DEVICE;
    }
    uvc_device_t *uvc_dev = malloc(sizeof(*uvc_dev));
    if (!uvc_dev) {
        libusb_unref_device(found); // 释放设备引用
        return UVC_ERROR_NO_MEM;
    }
    uvc_dev->ctx = ctx;
    uvc_dev->ref = 0;
    uvc_dev->usb_dev = found;
    uvc_ref_device(uvc_dev);
    *dev = uvc_dev;
    return UVC_SUCCESS;
}

/** @brief Finds all cameras identified by vendor, product and/or serial number
 * @ingroup device
 *
 * @param[in] ctx UVC context in which to search for the camera
 * @param[out] devs List of matching cameras
 * @param[in] vid Vendor ID number, optional
 * @param[in] pid Product ID number, optional
 * @param[in] sn Serial number or NULL
 * @return Error finding device or UVC_SUCCESS
 */
uvc_error_t uvc_find_devices(uvc_context_t *ctx, uvc_device_t ***devs, int vid, int pid, const char *sn) {
    uvc_error_t ret = UVC_SUCCESS;

    uvc_device_t **list;
    uvc_device_t *test_dev;
    int dev_idx;
    int found_dev;

    uvc_device_t **list_internal;
    int num_uvc_devices;

    UVC_ENTER();

    ret = uvc_get_device_list(ctx, &list);

    if (ret != UVC_SUCCESS) {
        UVC_EXIT(ret);
        return ret;
    }

    num_uvc_devices = 0;
    dev_idx = 0;
    found_dev = 0;

    list_internal = malloc(sizeof(*list_internal));
    *list_internal = NULL;

    while ((test_dev = list[dev_idx++]) != NULL) {
        uvc_device_descriptor_t *desc;

        if (uvc_get_device_descriptor(test_dev, &desc) != UVC_SUCCESS)
            continue;

        if ((!vid || desc->idVendor == vid) && (!pid || desc->idProduct == pid) &&
            (!sn || (desc->serialNumber && !strcmp(desc->serialNumber, sn)))) {
            found_dev = 1;
            uvc_ref_device(test_dev);

            num_uvc_devices++;
            list_internal = realloc(list_internal, (num_uvc_devices + 1) * sizeof(*list_internal));

            list_internal[num_uvc_devices - 1] = test_dev;
            list_internal[num_uvc_devices] = NULL;
        }

        uvc_free_device_descriptor(desc);
    }

    uvc_free_device_list(list, 1);

    if (found_dev) {
        *devs = list_internal;
        UVC_EXIT(UVC_SUCCESS);
        return UVC_SUCCESS;
    } else {
        UVC_EXIT(UVC_ERROR_NO_DEVICE);
        return UVC_ERROR_NO_DEVICE;
    }
}

/** @brief Get the number of the bus to which the device is attached
 * @ingroup device
 */
uint8_t uvc_get_bus_number(uvc_device_t *dev) { return libusb_get_bus_number(dev->usb_dev); }

/** @brief Get the number assigned to the device within its bus
 * @ingroup device
 */
uint8_t uvc_get_device_address(uvc_device_t *dev) { return libusb_get_device_address(dev->usb_dev); }

static uvc_error_t uvc_open_internal(uvc_device_t *dev, struct libusb_device_handle *usb_devh,
                                     uvc_device_handle_t **devh);

#if LIBUSB_API_VERSION >= 0x01000107
/** @brief Wrap a platform-specific system device handle and obtain a UVC device handle.
 * The handle allows you to use libusb to perform I/O on the device in question.
 *
 * On Linux, the system device handle must be a valid file descriptor opened on the device node.
 *
 * The system device handle must remain open until uvc_close() is called. The system device handle will not be closed by
 * uvc_close().
 * @ingroup device
 *
 * @param sys_dev the platform-specific system device handle
 * @param context UVC context to prepare the device
 * @param[out] devh Handle on opened device
 * @return Error opening device or SUCCESS
 */
uvc_error_t uvc_wrap(int sys_dev, uvc_context_t *context, uvc_device_handle_t **devh) {
    uvc_error_t ret;
    struct libusb_device_handle *usb_devh;

    UVC_ENTER();

    uvc_device_t *dev = NULL;
    int err = libusb_wrap_sys_device(context->usb_ctx, sys_dev, &usb_devh);
    UVC_DEBUG("libusb_wrap_sys_device() = %d", err);
    if (err != LIBUSB_SUCCESS) {
        UVC_EXIT(err);
        return err;
    }

    dev = calloc(1, sizeof(uvc_device_t));
    dev->ctx = context;
    dev->usb_dev = libusb_get_device(usb_devh);

    ret = uvc_open_internal(dev, usb_devh, devh);
    UVC_EXIT(ret);
    return ret;
}
#endif

uvc_error_t uvc_wrap(int sys_dev, uvc_context_t *context, uvc_device_handle_t **devh);


/** @brief Open a UVC device
 * @ingroup device
 *
 * @param dev Device to open
 * @param[out] devh Handle on opened device
 * @return Error opening device or SUCCESS
 */
uvc_error_t uvc_open(uvc_device_t *dev, uvc_device_handle_t **devh) {
    uvc_error_t ret;
    struct libusb_device_handle *usb_devh;

    UVC_ENTER();

    ret = libusb_open(dev->usb_dev, &usb_devh);
    UVC_DEBUG("libusb_open() = %d", ret);

    if (ret != UVC_SUCCESS) {
        UVC_EXIT(ret);
        return ret;
    }

    ret = uvc_open_internal(dev, usb_devh, devh);
    UVC_EXIT(ret);
    return ret;
}

static uvc_error_t uvc_open_internal(uvc_device_t *dev, struct libusb_device_handle *usb_devh,
                                     uvc_device_handle_t **devh) {
    uvc_error_t ret;
    uvc_device_handle_t *internal_devh;
    struct libusb_device_descriptor desc;

    UVC_ENTER();

    uvc_ref_device(dev);

    internal_devh = calloc(1, sizeof(*internal_devh));
    internal_devh->dev = dev;
    internal_devh->usb_devh = usb_devh;

    ret = uvc_get_device_info(internal_devh, &(internal_devh->info));

    if (ret != UVC_SUCCESS)
        goto fail;

    UVC_DEBUG("claiming control interface %d", internal_devh->info->ctrl_if.bInterfaceNumber);
    ret = uvc_claim_if(internal_devh, internal_devh->info->ctrl_if.bInterfaceNumber);
    if (ret != UVC_SUCCESS)
        goto fail;

    libusb_get_device_descriptor(dev->usb_dev, &desc);
    internal_devh->is_isight = (desc.idVendor == 0x05ac && desc.idProduct == 0x8501);

    if (internal_devh->info->ctrl_if.bEndpointAddress) {
        internal_devh->status_xfer = libusb_alloc_transfer(0);
        if (!internal_devh->status_xfer) {
            ret = UVC_ERROR_NO_MEM;
            goto fail;
        }

        libusb_fill_interrupt_transfer(internal_devh->status_xfer, usb_devh,
                                       internal_devh->info->ctrl_if.bEndpointAddress, internal_devh->status_buf,
                                       sizeof(internal_devh->status_buf), _uvc_status_callback, internal_devh, 0);
        ret = libusb_submit_transfer(internal_devh->status_xfer);
        UVC_DEBUG("libusb_submit_transfer() = %d", ret);

        if (ret) {
            fprintf(stderr, "uvc: device has a status interrupt endpoint, but unable to read from it\n");
            goto fail;
        }
    }

    if (dev->ctx->own_usb_ctx && dev->ctx->open_devices == NULL) {
        /* Since this is our first device, we need to spawn the event handler thread */
        uvc_start_handler_thread(dev->ctx);
    }

    DL_APPEND(dev->ctx->open_devices, internal_devh);
    *devh = internal_devh;

    UVC_EXIT(ret);

    return ret;

fail:
    if (internal_devh->info) {
        uvc_release_if(internal_devh, internal_devh->info->ctrl_if.bInterfaceNumber);
    }
    libusb_close(usb_devh);
    uvc_unref_device(dev);
    uvc_free_devh(internal_devh);

    UVC_EXIT(ret);

    return ret;
}

/**
 * @internal
 * @brief Parses the complete device descriptor for a device
 * @ingroup device
 * @note Free *info with uvc_free_device_info when you're done
 *
 * @param dev Device to parse descriptor for
 * @param info Where to store a pointer to the new info struct
 */
uvc_error_t uvc_get_device_info(uvc_device_handle_t *devh, uvc_device_info_t **info) {
    uvc_error_t ret;
    uvc_device_info_t *internal_info;

    UVC_ENTER();

    internal_info = calloc(1, sizeof(*internal_info));
    if (!internal_info) {
        UVC_EXIT(UVC_ERROR_NO_MEM);
        return UVC_ERROR_NO_MEM;
    }

    if (libusb_get_config_descriptor(devh->dev->usb_dev, 0, &(internal_info->config)) != 0) {
        free(internal_info);
        UVC_EXIT(UVC_ERROR_IO);
        return UVC_ERROR_IO;
    }

    ret = uvc_scan_control(devh, internal_info);
    if (ret != UVC_SUCCESS) {
        uvc_free_device_info(internal_info);
        UVC_EXIT(ret);
        return ret;
    }

    *info = internal_info;

    UVC_EXIT(ret);
    return ret;
}

/**
 * @internal
 * @brief Frees the device descriptor for a device
 * @ingroup device
 *
 * @param info Which device info block to free
 */
void uvc_free_device_info(uvc_device_info_t *info) {
    uvc_input_terminal_t *input_term, *input_term_tmp;
    uvc_processing_unit_t *proc_unit, *proc_unit_tmp;
    uvc_extension_unit_t *ext_unit, *ext_unit_tmp;

    uvc_streaming_interface_t *stream_if, *stream_if_tmp;
    uvc_format_desc_t *format, *format_tmp;
    uvc_frame_desc_t *frame, *frame_tmp;
    uvc_still_frame_desc_t *still_frame, *still_frame_tmp;
    uvc_still_frame_res_t *still_res, *still_res_tmp;

    UVC_ENTER();

    DL_FOREACH_SAFE(info->ctrl_if.input_term_descs, input_term, input_term_tmp) {
        DL_DELETE(info->ctrl_if.input_term_descs, input_term);
        free(input_term);
    }

    DL_FOREACH_SAFE(info->ctrl_if.processing_unit_descs, proc_unit, proc_unit_tmp) {
        DL_DELETE(info->ctrl_if.processing_unit_descs, proc_unit);
        free(proc_unit);
    }

    DL_FOREACH_SAFE(info->ctrl_if.extension_unit_descs, ext_unit, ext_unit_tmp) {
        DL_DELETE(info->ctrl_if.extension_unit_descs, ext_unit);
        free(ext_unit);
    }

    DL_FOREACH_SAFE(info->stream_ifs, stream_if, stream_if_tmp) {
        DL_FOREACH_SAFE(stream_if->format_descs, format, format_tmp) {
            DL_FOREACH_SAFE(format->frame_descs, frame, frame_tmp) {
                if (frame->intervals)
                    free(frame->intervals);

                DL_DELETE(format->frame_descs, frame);
                free(frame);
            }

            if (format->still_frame_desc) {
                DL_FOREACH_SAFE(format->still_frame_desc, still_frame, still_frame_tmp) {
                    DL_FOREACH_SAFE(still_frame->imageSizePatterns, still_res, still_res_tmp) { free(still_res); }

                    if (still_frame->bCompression) {
                        free(still_frame->bCompression);
                    }
                    free(still_frame);
                }
            }

            DL_DELETE(stream_if->format_descs, format);
            free(format);
        }

        DL_DELETE(info->stream_ifs, stream_if);
        free(stream_if);
    }

    if (info->config)
        libusb_free_config_descriptor(info->config);

    free(info);

    UVC_EXIT_VOID();
}

static uvc_error_t get_device_descriptor(uvc_device_handle_t *devh, uvc_device_descriptor_t **desc) {
    uvc_device_descriptor_t *desc_internal;
    struct libusb_device_descriptor usb_desc;
    struct libusb_device_handle *usb_devh = devh->usb_devh;
    uvc_error_t ret;

    UVC_ENTER();

    ret = libusb_get_device_descriptor(devh->dev->usb_dev, &usb_desc);

    if (ret != UVC_SUCCESS) {
        UVC_EXIT(ret);
        return ret;
    }

    desc_internal = calloc(1, sizeof(*desc_internal));
    desc_internal->idVendor = usb_desc.idVendor;
    desc_internal->idProduct = usb_desc.idProduct;

    unsigned char buf[64];

    int bytes = libusb_get_string_descriptor_ascii(usb_devh, usb_desc.iSerialNumber, buf, sizeof(buf));

    if (bytes > 0)
        desc_internal->serialNumber = strdup((const char *)buf);

    bytes = libusb_get_string_descriptor_ascii(usb_devh, usb_desc.iManufacturer, buf, sizeof(buf));

    if (bytes > 0)
        desc_internal->manufacturer = strdup((const char *)buf);

    bytes = libusb_get_string_descriptor_ascii(usb_devh, usb_desc.iProduct, buf, sizeof(buf));

    if (bytes > 0)
        desc_internal->product = strdup((const char *)buf);

    *desc = desc_internal;

    UVC_EXIT(ret);
    return ret;
}

/**
 * @brief Get a descriptor that contains the general information about
 * a device
 * @ingroup device
 *
 * Free *desc with uvc_free_device_descriptor when you're done.
 *
 * @param dev Device to fetch information about
 * @param[out] desc Descriptor structure
 * @return Error if unable to fetch information, else SUCCESS
 */
uvc_error_t uvc_get_device_descriptor(uvc_device_t *dev, uvc_device_descriptor_t **desc) {
    uvc_device_descriptor_t *desc_internal;
    struct libusb_device_descriptor usb_desc;
    struct libusb_device_handle *usb_devh;
    uvc_error_t ret;

    UVC_ENTER();

    ret = libusb_get_device_descriptor(dev->usb_dev, &usb_desc);

    if (ret != UVC_SUCCESS) {
        UVC_EXIT(ret);
        return ret;
    }
    desc_internal = calloc(1, sizeof(*desc_internal));
    desc_internal->idVendor = usb_desc.idVendor;
    desc_internal->idProduct = usb_desc.idProduct;

    if (libusb_open(dev->usb_dev, &usb_devh) == 0) {
        unsigned char buf[64];
        int bytes = libusb_get_string_descriptor_ascii(usb_devh, usb_desc.iSerialNumber, buf, sizeof(buf));
        if (bytes > 0) {
            desc_internal->serialNumber = strdup((const char *)buf);
        }

        bytes = libusb_get_string_descriptor_ascii(usb_devh, usb_desc.iManufacturer, buf, sizeof(buf));

        if (bytes > 0)
            desc_internal->manufacturer = strdup((const char *)buf);

        bytes = libusb_get_string_descriptor_ascii(usb_devh, usb_desc.iProduct, buf, sizeof(buf));

        if (bytes > 0)
            desc_internal->product = strdup((const char *)buf);

        libusb_close(usb_devh);
    } else {
        UVC_DEBUG("can't open device %04x:%04x, not fetching serial etc.", usb_desc.idVendor, usb_desc.idProduct);
    }

    *desc = desc_internal;

    UVC_EXIT(ret);
    return ret;
}

/**
 * @brief Frees a device descriptor created with uvc_get_device_descriptor
 * @ingroup device
 *
 * @param desc Descriptor to free
 */
void uvc_free_device_descriptor(uvc_device_descriptor_t *desc) {
    UVC_ENTER();

    if (desc->serialNumber)
        free((void *)desc->serialNumber);

    if (desc->manufacturer)
        free((void *)desc->manufacturer);

    if (desc->product)
        free((void *)desc->product);

    free(desc);

    UVC_EXIT_VOID();
}

/**
 * @brief Get a list of the UVC devices attached to the system
 * @ingroup device
 *
 * @note Free the list with uvc_free_device_list when you're done.
 *
 * @param ctx UVC context in which to list devices
 * @param list List of uvc_device structures
 * @return Error if unable to list devices, else SUCCESS
 */
uvc_error_t uvc_get_device_list(uvc_context_t *ctx, uvc_device_t ***list) {
    struct libusb_device **usb_dev_list;
    struct libusb_device *usb_dev;
    int num_usb_devices;

    uvc_device_t **list_internal;
    int num_uvc_devices;

    /* per device */
    int dev_idx;
    struct libusb_config_descriptor *config;
    struct libusb_device_descriptor desc;
    uint8_t got_interface;

    /* per interface */
    int interface_idx;
    const struct libusb_interface *interface;

    /* per altsetting */
    int altsetting_idx;
    const struct libusb_interface_descriptor *if_desc;

    UVC_ENTER();

    num_usb_devices = libusb_get_device_list(ctx->usb_ctx, &usb_dev_list);

    if (num_usb_devices < 0) {
        UVC_EXIT(UVC_ERROR_IO);
        return UVC_ERROR_IO;
    }

    list_internal = malloc(sizeof(*list_internal));
    *list_internal = NULL;

    num_uvc_devices = 0;
    dev_idx = -1;

    while ((usb_dev = usb_dev_list[++dev_idx]) != NULL) {
        got_interface = 0;

        if (libusb_get_config_descriptor(usb_dev, 0, &config) != 0)
            continue;

        if (libusb_get_device_descriptor(usb_dev, &desc) != LIBUSB_SUCCESS)
            continue;

        for (interface_idx = 0; !got_interface && interface_idx < config->bNumInterfaces; ++interface_idx) {
            interface = &config->interface[interface_idx];

            for (altsetting_idx = 0; !got_interface && altsetting_idx < interface->num_altsetting; ++altsetting_idx) {
                if_desc = &interface->altsetting[altsetting_idx];

                // Skip TIS cameras that definitely aren't UVC even though they might
                // look that way

                if (0x199e == desc.idVendor && desc.idProduct >= 0x8201 && desc.idProduct <= 0x8208) {
                    continue;
                }

                // Special case for Imaging Source cameras
                /* Video, Streaming */
                if (0x199e == desc.idVendor && (0x8101 == desc.idProduct || 0x8102 == desc.idProduct) &&
                    if_desc->bInterfaceClass == 255 && if_desc->bInterfaceSubClass == 2) {
                    got_interface = 1;
                }

                /* Video, Streaming */
                if (if_desc->bInterfaceClass == 14 && if_desc->bInterfaceSubClass == 2) {
                    got_interface = 1;
                }
            }
        }

        libusb_free_config_descriptor(config);

        if (got_interface) {
            uvc_device_t *uvc_dev = malloc(sizeof(*uvc_dev));
            uvc_dev->ctx = ctx;
            uvc_dev->ref = 0;
            uvc_dev->usb_dev = usb_dev;
            uvc_ref_device(uvc_dev);

            num_uvc_devices++;
            list_internal = realloc(list_internal, (num_uvc_devices + 1) * sizeof(*list_internal));

            list_internal[num_uvc_devices - 1] = uvc_dev;
            list_internal[num_uvc_devices] = NULL;

            UVC_DEBUG("    UVC: %d", dev_idx);
        } else {
            UVC_DEBUG("non-UVC: %d", dev_idx);
        }
    }

    libusb_free_device_list(usb_dev_list, 1);

    *list = list_internal;

    UVC_EXIT(UVC_SUCCESS);
    return UVC_SUCCESS;
}

/**
 * @brief Frees a list of device structures created with uvc_get_device_list.
 * @ingroup device
 *
 * @param list Device list to free
 * @param unref_devices Decrement the reference counter for each device
 * in the list, and destroy any entries that end up with zero references
 */
void uvc_free_device_list(uvc_device_t **list, uint8_t unref_devices) {
    uvc_device_t *dev;
    int dev_idx = 0;

    UVC_ENTER();

    if (unref_devices) {
        while ((dev = list[dev_idx++]) != NULL) {
            uvc_unref_device(dev);
        }
    }

    free(list);

    UVC_EXIT_VOID();
}

/**
 * @brief Get the uvc_device_t corresponding to an open device
 * @ingroup device
 *
 * @note Unref the uvc_device_t when you're done with it
 *
 * @param devh Device handle to an open UVC device
 */
uvc_device_t *uvc_get_device(uvc_device_handle_t *devh) {
    uvc_ref_device(devh->dev);
    return devh->dev;
}

/**
 * @brief Get the underlying libusb device handle for an open device
 * @ingroup device
 *
 * This can be used to access other interfaces on the same device, e.g.
 * a webcam microphone.
 *
 * @note The libusb device handle is only valid while the UVC device is open;
 * it will be invalidated upon calling uvc_close.
 *
 * @param devh UVC device handle to an open device
 */
libusb_device_handle *uvc_get_libusb_handle(uvc_device_handle_t *devh) { return devh->usb_devh; }

/**
 * @brief Get camera terminal descriptor for the open device.
 *
 * @note Do not modify the returned structure.
 * @note The returned structure is part of a linked list, but iterating through
 * it will make it no longer the camera terminal
 *
 * @param devh Device handle to an open UVC device
 */
const uvc_input_terminal_t *uvc_get_camera_terminal(uvc_device_handle_t *devh) {
    const uvc_input_terminal_t *term = uvc_get_input_terminals(devh);
    while (term != NULL) {
        if (term->wTerminalType == UVC_ITT_CAMERA) {
            break;
        } else {
            term = term->next;
        }
    }
    return term;
}


/**
 * @brief Get input terminal descriptors for the open device.
 *
 * @note Do not modify the returned structure.
 * @note The returned structure is part of a linked list. Iterate through
 *       it by using the 'next' pointers.
 *
 * @param devh Device handle to an open UVC device
 */
const uvc_input_terminal_t *uvc_get_input_terminals(uvc_device_handle_t *devh) {
    return devh->info->ctrl_if.input_term_descs;
}

/**
 * @brief Get output terminal descriptors for the open device.
 *
 * @note Do not modify the returned structure.
 * @note The returned structure is part of a linked list. Iterate through
 *       it by using the 'next' pointers.
 *
 * @param devh Device handle to an open UVC device
 */
const uvc_output_terminal_t *uvc_get_output_terminals(uvc_device_handle_t *devh) { return NULL; /* @todo */ }

/**
 * @brief Get selector unit descriptors for the open device.
 *
 * @note Do not modify the returned structure.
 * @note The returned structure is part of a linked list. Iterate through
 *       it by using the 'next' pointers.
 *
 * @param devh Device handle to an open UVC device
 */
const uvc_selector_unit_t *uvc_get_selector_units(uvc_device_handle_t *devh) {
    return devh->info->ctrl_if.selector_unit_descs;
}

/**
 * @brief Get processing unit descriptors for the open device.
 *
 * @note Do not modify the returned structure.
 * @note The returned structure is part of a linked list. Iterate through
 *       it by using the 'next' pointers.
 *
 * @param devh Device handle to an open UVC device
 */
const uvc_processing_unit_t *uvc_get_processing_units(uvc_device_handle_t *devh) {
    return devh->info->ctrl_if.processing_unit_descs;
}

/**
 * @brief Get extension unit descriptors for the open device.
 *
 * @note Do not modify the returned structure.
 * @note The returned structure is part of a linked list. Iterate through
 *       it by using the 'next' pointers.
 *
 * @param devh Device handle to an open UVC device
 */
const uvc_extension_unit_t *uvc_get_extension_units(uvc_device_handle_t *devh) {
    return devh->info->ctrl_if.extension_unit_descs;
}

/**
 * @brief Increment the reference count for a device
 * @ingroup device
 *
 * @param dev Device to reference
 */
void uvc_ref_device(uvc_device_t *dev) {
    UVC_ENTER();

    dev->ref++;
    libusb_ref_device(dev->usb_dev);

    UVC_EXIT_VOID();
}

/**
 * @brief Decrement the reference count for a device
 * @ingropu device
 * @note If the count reaches zero, the device will be discarded
 *
 * @param dev Device to unreference
 */
void uvc_unref_device(uvc_device_t *dev) {
    UVC_ENTER();

    libusb_unref_device(dev->usb_dev);
    dev->ref--;

    if (dev->ref == 0)
        free(dev);

    UVC_EXIT_VOID();
}

/** @internal
 * Claim a UVC interface, detaching the kernel driver if necessary.
 * @ingroup device
 *
 * @param devh UVC device handle
 * @param idx UVC interface index
 */
uvc_error_t uvc_claim_if(uvc_device_handle_t *devh, int idx) {
    int ret = UVC_SUCCESS;

    UVC_ENTER();

    if (devh->claimed & (1 << idx)) {
        UVC_DEBUG("attempt to claim already-claimed interface %d\n", idx);
        UVC_EXIT(ret);
        return ret;
    }

    /* Tell libusb to detach any active kernel drivers. libusb will keep track of whether
     * it found a kernel driver for this interface. */
    ret = libusb_detach_kernel_driver(devh->usb_devh, idx);

    if (ret == UVC_SUCCESS || ret == LIBUSB_ERROR_NOT_FOUND || ret == LIBUSB_ERROR_NOT_SUPPORTED) {
        UVC_DEBUG("claiming interface %d", idx);
        if (!(ret = libusb_claim_interface(devh->usb_devh, idx))) {
            devh->claimed |= (1 << idx);
        }
    } else {
        UVC_DEBUG("not claiming interface %d: unable to detach kernel driver (%s)", idx, uvc_strerror(ret));
    }

    UVC_EXIT(ret);
    return ret;
}

/** @internal
 * Release a UVC interface.
 * @ingroup device
 *
 * @param devh UVC device handle
 * @param idx UVC interface index
 */
uvc_error_t uvc_release_if(uvc_device_handle_t *devh, int idx) {
    int ret = UVC_SUCCESS;

    UVC_ENTER();
    UVC_DEBUG("releasing interface %d", idx);
    if (!(devh->claimed & (1 << idx))) {
        UVC_DEBUG("attempt to release unclaimed interface %d\n", idx);
        UVC_EXIT(ret);
        return ret;
    }

    /* libusb_release_interface *should* reset the alternate setting to the first available,
       but sometimes (e.g. on Darwin) it doesn't. Thus, we do it explicitly here.
       This is needed to de-initialize certain cameras. */
    libusb_set_interface_alt_setting(devh->usb_devh, idx, 0);
    ret = libusb_release_interface(devh->usb_devh, idx);

    if (UVC_SUCCESS == ret) {
        devh->claimed &= ~(1 << idx);
        /* Reattach any kernel drivers that were disabled when we claimed this interface */
        ret = libusb_attach_kernel_driver(devh->usb_devh, idx);

        if (ret == UVC_SUCCESS) {
            UVC_DEBUG("reattached kernel driver to interface %d", idx);
        } else if (ret == LIBUSB_ERROR_NOT_FOUND || ret == LIBUSB_ERROR_NOT_SUPPORTED) {
            ret = UVC_SUCCESS; /* NOT_FOUND and NOT_SUPPORTED are OK: nothing to do */
        } else {
            UVC_DEBUG("error reattaching kernel driver to interface %d: %s", idx, uvc_strerror(ret));
        }
    }

    UVC_EXIT(ret);
    return ret;
}

/** @internal
 * Find a device's VideoControl interface and process its descriptor
 * @ingroup device
 */
uvc_error_t uvc_scan_control(uvc_device_handle_t *devh, uvc_device_info_t *info) {
    const struct libusb_interface_descriptor *if_desc;
    uvc_error_t parse_ret, ret;
    int interface_idx;
    const unsigned char *buffer;
    size_t buffer_left, block_size;

    UVC_ENTER();

    ret = UVC_SUCCESS;
    if_desc = NULL;

    uvc_device_descriptor_t *dev_desc;
    int haveTISCamera = 0;
    get_device_descriptor(devh, &dev_desc);
    if (0x199e == dev_desc->idVendor && (0x8101 == dev_desc->idProduct || 0x8102 == dev_desc->idProduct)) {
        haveTISCamera = 1;
    }
    uvc_free_device_descriptor(dev_desc);

    for (interface_idx = 0; interface_idx < info->config->bNumInterfaces; ++interface_idx) {
        if_desc = &info->config->interface[interface_idx].altsetting[0];

        if (haveTISCamera && if_desc->bInterfaceClass == 255 && if_desc->bInterfaceSubClass == 1) // Video, Control
            break;

        if (if_desc->bInterfaceClass == 14 && if_desc->bInterfaceSubClass == 1) // Video, Control
            break;

        if_desc = NULL;
    }

    if (if_desc == NULL) {
        UVC_EXIT(UVC_ERROR_INVALID_DEVICE);
        return UVC_ERROR_INVALID_DEVICE;
    }

    info->ctrl_if.bInterfaceNumber = interface_idx;
    if (if_desc->bNumEndpoints != 0) {
        info->ctrl_if.bEndpointAddress = if_desc->endpoint[0].bEndpointAddress;
    }

    buffer = if_desc->extra;
    buffer_left = if_desc->extra_length;

    while (buffer_left >= 3) { // parseX needs to see buf[0,2] = length,type
        block_size = buffer[0];
        parse_ret = uvc_parse_vc(devh->dev, info, buffer, block_size);

        if (parse_ret != UVC_SUCCESS) {
            ret = parse_ret;
            break;
        }

        buffer_left -= block_size;
        buffer += block_size;
    }

    UVC_EXIT(ret);
    return ret;
}

/** @internal
 * @brief Parse a VideoControl header.
 * @ingroup device
 */
uvc_error_t uvc_parse_vc_header(uvc_device_t *dev, uvc_device_info_t *info, const unsigned char *block,
                                size_t block_size) {
    size_t i;
    uvc_error_t scan_ret, ret = UVC_SUCCESS;

    UVC_ENTER();

    /*
    int uvc_version;
    uvc_version = (block[4] >> 4) * 1000 + (block[4] & 0x0f) * 100
      + (block[3] >> 4) * 10 + (block[3] & 0x0f);
    */

    info->ctrl_if.bcdUVC = SW_TO_SHORT(&block[3]);

    switch (info->ctrl_if.bcdUVC) {
    case 0x0100:
        info->ctrl_if.dwClockFrequency = DW_TO_INT(block + 7);
        break;
    case 0x010a:
        info->ctrl_if.dwClockFrequency = DW_TO_INT(block + 7);
        break;
    case 0x0110:
        break;
    default:
        UVC_EXIT(UVC_ERROR_NOT_SUPPORTED);
        return UVC_ERROR_NOT_SUPPORTED;
    }

    for (i = 12; i < block_size; ++i) {
        scan_ret = uvc_scan_streaming(dev, info, block[i]);
        if (scan_ret != UVC_SUCCESS) {
            ret = scan_ret;
            break;
        }
    }

    UVC_EXIT(ret);
    return ret;
}

/** @internal
 * @brief Parse a VideoControl input terminal.
 * @ingroup device
 */
uvc_error_t uvc_parse_vc_input_terminal(uvc_device_t *dev, uvc_device_info_t *info, const unsigned char *block,
                                        size_t block_size) {
    uvc_input_terminal_t *term;
    size_t i;

    UVC_ENTER();

    /* only supporting camera-type input terminals */
    if (SW_TO_SHORT(&block[4]) != UVC_ITT_CAMERA) {
        UVC_EXIT(UVC_SUCCESS);
        return UVC_SUCCESS;
    }

    term = calloc(1, sizeof(*term));

    term->bTerminalID = block[3];
    term->wTerminalType = SW_TO_SHORT(&block[4]);
    term->wObjectiveFocalLengthMin = SW_TO_SHORT(&block[8]);
    term->wObjectiveFocalLengthMax = SW_TO_SHORT(&block[10]);
    term->wOcularFocalLength = SW_TO_SHORT(&block[12]);

    for (i = 14 + block[14]; i >= 15; --i)
        term->bmControls = block[i] + (term->bmControls << 8);

    DL_APPEND(info->ctrl_if.input_term_descs, term);

    UVC_EXIT(UVC_SUCCESS);
    return UVC_SUCCESS;
}

/** @internal
 * @brief Parse a VideoControl processing unit.
 * @ingroup device
 */
uvc_error_t uvc_parse_vc_processing_unit(uvc_device_t *dev, uvc_device_info_t *info, const unsigned char *block,
                                         size_t block_size) {
    uvc_processing_unit_t *unit;
    size_t i;

    UVC_ENTER();

    unit = calloc(1, sizeof(*unit));
    unit->bUnitID = block[3];
    unit->bSourceID = block[4];

    for (i = 7 + block[7]; i >= 8; --i)
        unit->bmControls = block[i] + (unit->bmControls << 8);

    DL_APPEND(info->ctrl_if.processing_unit_descs, unit);

    UVC_EXIT(UVC_SUCCESS);
    return UVC_SUCCESS;
}

/** @internal
 * @brief Parse a VideoControl selector unit.
 * @ingroup device
 */
uvc_error_t uvc_parse_vc_selector_unit(uvc_device_t *dev, uvc_device_info_t *info, const unsigned char *block,
                                       size_t block_size) {
    uvc_selector_unit_t *unit;

    UVC_ENTER();

    unit = calloc(1, sizeof(*unit));
    unit->bUnitID = block[3];

    DL_APPEND(info->ctrl_if.selector_unit_descs, unit);

    UVC_EXIT(UVC_SUCCESS);
    return UVC_SUCCESS;
}

/** @internal
 * @brief Parse a VideoControl extension unit.
 * @ingroup device
 */
uvc_error_t uvc_parse_vc_extension_unit(uvc_device_t *dev, uvc_device_info_t *info, const unsigned char *block,
                                        size_t block_size) {
    uvc_extension_unit_t *unit = calloc(1, sizeof(*unit));
    const uint8_t *start_of_controls;
    int size_of_controls, num_in_pins;
    int i;

    UVC_ENTER();

    unit->bUnitID = block[3];
    memcpy(unit->guidExtensionCode, &block[4], 16);

    num_in_pins = block[21];
    size_of_controls = block[22 + num_in_pins];
    start_of_controls = &block[23 + num_in_pins];

    for (i = size_of_controls - 1; i >= 0; --i)
        unit->bmControls = start_of_controls[i] + (unit->bmControls << 8);

    DL_APPEND(info->ctrl_if.extension_unit_descs, unit);

    UVC_EXIT(UVC_SUCCESS);
    return UVC_SUCCESS;
}

/** @internal
 * Process a single VideoControl descriptor block
 * @ingroup device
 */
uvc_error_t uvc_parse_vc(uvc_device_t *dev, uvc_device_info_t *info, const unsigned char *block, size_t block_size) {
    int descriptor_subtype;
    uvc_error_t ret = UVC_SUCCESS;

    UVC_ENTER();

    if (block[1] != 36) { // not a CS_INTERFACE descriptor??
        UVC_EXIT(UVC_SUCCESS);
        return UVC_SUCCESS; // UVC_ERROR_INVALID_DEVICE;
    }

    descriptor_subtype = block[2];

    switch (descriptor_subtype) {
    case UVC_VC_HEADER:
        ret = uvc_parse_vc_header(dev, info, block, block_size);
        break;
    case UVC_VC_INPUT_TERMINAL:
        ret = uvc_parse_vc_input_terminal(dev, info, block, block_size);
        break;
    case UVC_VC_OUTPUT_TERMINAL:
        break;
    case UVC_VC_SELECTOR_UNIT:
        ret = uvc_parse_vc_selector_unit(dev, info, block, block_size);
        break;
    case UVC_VC_PROCESSING_UNIT:
        ret = uvc_parse_vc_processing_unit(dev, info, block, block_size);
        break;
    case UVC_VC_EXTENSION_UNIT:
        ret = uvc_parse_vc_extension_unit(dev, info, block, block_size);
        break;
    default:
        ret = UVC_ERROR_INVALID_DEVICE;
    }

    UVC_EXIT(ret);
    return ret;
}

/** @internal
 * Process a VideoStreaming interface
 * @ingroup device
 */
uvc_error_t uvc_scan_streaming(uvc_device_t *dev, uvc_device_info_t *info, int interface_idx) {
    const struct libusb_interface_descriptor *if_desc;
    const unsigned char *buffer;
    size_t buffer_left, block_size;
    uvc_error_t ret, parse_ret;
    uvc_streaming_interface_t *stream_if;

    UVC_ENTER();

    ret = UVC_SUCCESS;

    if_desc = &(info->config->interface[interface_idx].altsetting[0]);
    buffer = if_desc->extra;
    buffer_left = if_desc->extra_length;

    stream_if = calloc(1, sizeof(*stream_if));
    stream_if->parent = info;
    stream_if->bInterfaceNumber = if_desc->bInterfaceNumber;
    DL_APPEND(info->stream_ifs, stream_if);

    while (buffer_left >= 3) {
        block_size = buffer[0];
        parse_ret = uvc_parse_vs(dev, info, stream_if, buffer, block_size);

        if (parse_ret != UVC_SUCCESS) {
            ret = parse_ret;
            break;
        }

        buffer_left -= block_size;
        buffer += block_size;
    }

    UVC_EXIT(ret);
    return ret;
}

/** @internal
 * @brief Parse a VideoStreaming header block.
 * @ingroup device
 */
uvc_error_t uvc_parse_vs_input_header(uvc_streaming_interface_t *stream_if, const unsigned char *block,
                                      size_t block_size) {
    UVC_ENTER();

    stream_if->bEndpointAddress = block[6] & 0x8f;
    stream_if->bTerminalLink = block[8];
    stream_if->bStillCaptureMethod = block[9];

    UVC_EXIT(UVC_SUCCESS);
    return UVC_SUCCESS;
}

/** @internal
 * @brief Parse a VideoStreaming uncompressed format block.
 * @ingroup device
 */
uvc_error_t uvc_parse_vs_format_uncompressed(uvc_streaming_interface_t *stream_if, const unsigned char *block,
                                             size_t block_size) {
    UVC_ENTER();

    uvc_format_desc_t *format = calloc(1, sizeof(*format));

    format->parent = stream_if;
    format->bDescriptorSubtype = block[2];
    format->bFormatIndex = block[3];
    // format->bmCapabilities = block[4];
    // format->bmFlags = block[5];
    memcpy(format->guidFormat, &block[5], 16);
    format->bBitsPerPixel = block[21];
    format->bDefaultFrameIndex = block[22];
    format->bAspectRatioX = block[23];
    format->bAspectRatioY = block[24];
    format->bmInterlaceFlags = block[25];
    format->bCopyProtect = block[26];

    DL_APPEND(stream_if->format_descs, format);

    UVC_EXIT(UVC_SUCCESS);
    return UVC_SUCCESS;
}

/** @internal
 * @brief Parse a VideoStreaming frame format block.
 * @ingroup device
 */
uvc_error_t uvc_parse_vs_frame_format(uvc_streaming_interface_t *stream_if, const unsigned char *block,
                                      size_t block_size) {
    UVC_ENTER();

    uvc_format_desc_t *format = calloc(1, sizeof(*format));

    format->parent = stream_if;
    format->bDescriptorSubtype = block[2];
    format->bFormatIndex = block[3];
    format->bNumFrameDescriptors = block[4];
    memcpy(format->guidFormat, &block[5], 16);
    format->bBitsPerPixel = block[21];
    format->bDefaultFrameIndex = block[22];
    format->bAspectRatioX = block[23];
    format->bAspectRatioY = block[24];
    format->bmInterlaceFlags = block[25];
    format->bCopyProtect = block[26];
    format->bVariableSize = block[27];

    DL_APPEND(stream_if->format_descs, format);

    UVC_EXIT(UVC_SUCCESS);
    return UVC_SUCCESS;
}

/** @internal
 * @brief Parse a VideoStreaming MJPEG format block.
 * @ingroup device
 */
uvc_error_t uvc_parse_vs_format_mjpeg(uvc_streaming_interface_t *stream_if, const unsigned char *block,
                                      size_t block_size) {
    UVC_ENTER();

    uvc_format_desc_t *format = calloc(1, sizeof(*format));

    format->parent = stream_if;
    format->bDescriptorSubtype = block[2];
    format->bFormatIndex = block[3];
    memcpy(format->fourccFormat, "MJPG", 4);
    format->bmFlags = block[5];
    format->bBitsPerPixel = 0;
    format->bDefaultFrameIndex = block[6];
    format->bAspectRatioX = block[7];
    format->bAspectRatioY = block[8];
    format->bmInterlaceFlags = block[9];
    format->bCopyProtect = block[10];

    DL_APPEND(stream_if->format_descs, format);

    UVC_EXIT(UVC_SUCCESS);
    return UVC_SUCCESS;
}

/** @internal
 * @brief Parse a VideoStreaming uncompressed frame block.
 * @ingroup device
 */
uvc_error_t uvc_parse_vs_frame_frame(uvc_streaming_interface_t *stream_if, const unsigned char *block,
                                     size_t block_size) {
    uvc_format_desc_t *format;
    uvc_frame_desc_t *frame;

    const unsigned char *p;
    int i;

    UVC_ENTER();

    format = stream_if->format_descs->prev;
    frame = calloc(1, sizeof(*frame));

    frame->parent = format;

    frame->bDescriptorSubtype = block[2];
    frame->bFrameIndex = block[3];
    frame->bmCapabilities = block[4];
    frame->wWidth = block[5] + (block[6] << 8);
    frame->wHeight = block[7] + (block[8] << 8);
    frame->dwMinBitRate = DW_TO_INT(&block[9]);
    frame->dwMaxBitRate = DW_TO_INT(&block[13]);
    frame->dwDefaultFrameInterval = DW_TO_INT(&block[17]);
    frame->bFrameIntervalType = block[21];
    frame->dwBytesPerLine = DW_TO_INT(&block[22]);

    if (block[21] == 0) {
        frame->dwMinFrameInterval = DW_TO_INT(&block[26]);
        frame->dwMaxFrameInterval = DW_TO_INT(&block[30]);
        frame->dwFrameIntervalStep = DW_TO_INT(&block[34]);
    } else {
        frame->intervals = calloc(block[21] + 1, sizeof(frame->intervals[0]));
        p = &block[26];

        for (i = 0; i < block[21]; ++i) {
            frame->intervals[i] = DW_TO_INT(p);
            p += 4;
        }
        frame->intervals[block[21]] = 0;
    }

    DL_APPEND(format->frame_descs, frame);

    UVC_EXIT(UVC_SUCCESS);
    return UVC_SUCCESS;
}

/** @internal
 * @brief Parse a VideoStreaming uncompressed frame block.
 * @ingroup device
 */
uvc_error_t uvc_parse_vs_frame_uncompressed(uvc_streaming_interface_t *stream_if, const unsigned char *block,
                                            size_t block_size) {
    uvc_format_desc_t *format;
    uvc_frame_desc_t *frame;

    const unsigned char *p;
    int i;

    UVC_ENTER();

    format = stream_if->format_descs->prev;
    frame = calloc(1, sizeof(*frame));

    frame->parent = format;

    frame->bDescriptorSubtype = block[2];
    frame->bFrameIndex = block[3];
    frame->bmCapabilities = block[4];
    frame->wWidth = block[5] + (block[6] << 8);
    frame->wHeight = block[7] + (block[8] << 8);
    frame->dwMinBitRate = DW_TO_INT(&block[9]);
    frame->dwMaxBitRate = DW_TO_INT(&block[13]);
    frame->dwMaxVideoFrameBufferSize = DW_TO_INT(&block[17]);
    frame->dwDefaultFrameInterval = DW_TO_INT(&block[21]);
    frame->bFrameIntervalType = block[25];

    if (block[25] == 0) {
        frame->dwMinFrameInterval = DW_TO_INT(&block[26]);
        frame->dwMaxFrameInterval = DW_TO_INT(&block[30]);
        frame->dwFrameIntervalStep = DW_TO_INT(&block[34]);
    } else {
        frame->intervals = calloc(block[25] + 1, sizeof(frame->intervals[0]));
        p = &block[26];

        for (i = 0; i < block[25]; ++i) {
            frame->intervals[i] = DW_TO_INT(p);
            p += 4;
        }
        frame->intervals[block[25]] = 0;
    }

    DL_APPEND(format->frame_descs, frame);

    UVC_EXIT(UVC_SUCCESS);
    return UVC_SUCCESS;
}

/** @internal
 * @brief Parse a VideoStreaming still iamge frame
 * @ingroup device
 */
uvc_error_t uvc_parse_vs_still_image_frame(uvc_streaming_interface_t *stream_if, const unsigned char *block,
                                           size_t block_size) {

    struct uvc_still_frame_desc *frame;
    uvc_format_desc_t *format;

    const unsigned char *p;
    int i;

    UVC_ENTER();

    format = stream_if->format_descs->prev;
    frame = calloc(1, sizeof(*frame));

    frame->parent = format;

    frame->bDescriptorSubtype = block[2];
    frame->bEndPointAddress = block[3];
    uint8_t numImageSizePatterns = block[4];

    frame->imageSizePatterns = NULL;

    p = &block[5];

    for (i = 1; i <= numImageSizePatterns; ++i) {
        uvc_still_frame_res_t *res = calloc(1, sizeof(uvc_still_frame_res_t));
        res->bResolutionIndex = i;
        res->wWidth = SW_TO_SHORT(p);
        p += 2;
        res->wHeight = SW_TO_SHORT(p);
        p += 2;

        DL_APPEND(frame->imageSizePatterns, res);
    }

    p = &block[5 + 4 * numImageSizePatterns];
    frame->bNumCompressionPattern = *p;

    if (frame->bNumCompressionPattern) {
        frame->bCompression = calloc(frame->bNumCompressionPattern, sizeof(frame->bCompression[0]));
        for (i = 0; i < frame->bNumCompressionPattern; ++i) {
            ++p;
            frame->bCompression[i] = *p;
        }
    } else {
        frame->bCompression = NULL;
    }

    DL_APPEND(format->still_frame_desc, frame);

    UVC_EXIT(UVC_SUCCESS);
    return UVC_SUCCESS;
}

/** @internal
 * Process a single VideoStreaming descriptor block
 * @ingroup device
 */
uvc_error_t uvc_parse_vs(uvc_device_t *dev, uvc_device_info_t *info, uvc_streaming_interface_t *stream_if,
                         const unsigned char *block, size_t block_size) {
    uvc_error_t ret;
    int descriptor_subtype;

    UVC_ENTER();

    ret = UVC_SUCCESS;
    descriptor_subtype = block[2];

    switch (descriptor_subtype) {
    case UVC_VS_INPUT_HEADER:
        ret = uvc_parse_vs_input_header(stream_if, block, block_size);
        break;
    case UVC_VS_OUTPUT_HEADER:
        UVC_DEBUG("unsupported descriptor subtype VS_OUTPUT_HEADER");
        break;
    case UVC_VS_STILL_IMAGE_FRAME:
        ret = uvc_parse_vs_still_image_frame(stream_if, block, block_size);
        break;
    case UVC_VS_FORMAT_UNCOMPRESSED:
        ret = uvc_parse_vs_format_uncompressed(stream_if, block, block_size);
        break;
    case UVC_VS_FORMAT_MJPEG:
        ret = uvc_parse_vs_format_mjpeg(stream_if, block, block_size);
        break;
    case UVC_VS_FRAME_UNCOMPRESSED:
    case UVC_VS_FRAME_MJPEG:
        ret = uvc_parse_vs_frame_uncompressed(stream_if, block, block_size);
        break;
    case UVC_VS_FORMAT_MPEG2TS:
        UVC_DEBUG("unsupported descriptor subtype VS_FORMAT_MPEG2TS");
        break;
    case UVC_VS_FORMAT_DV:
        UVC_DEBUG("unsupported descriptor subtype VS_FORMAT_DV");
        break;
    case UVC_VS_COLORFORMAT:
        UVC_DEBUG("unsupported descriptor subtype VS_COLORFORMAT");
        break;
    case UVC_VS_FORMAT_FRAME_BASED:
        ret = uvc_parse_vs_frame_format(stream_if, block, block_size);
        break;
    case UVC_VS_FRAME_FRAME_BASED:
        ret = uvc_parse_vs_frame_frame(stream_if, block, block_size);
        break;
    case UVC_VS_FORMAT_STREAM_BASED:
        UVC_DEBUG("unsupported descriptor subtype VS_FORMAT_STREAM_BASED");
        break;
    default:
        /** @todo handle JPEG and maybe still frames or even DV... */
        // UVC_DEBUG("unsupported descriptor subtype: %d",descriptor_subtype);
        break;
    }

    UVC_EXIT(ret);
    return ret;
}

/** @internal
 * @brief Free memory associated with a UVC device
 * @pre Streaming must be stopped, and threads must have died
 */
void uvc_free_devh(uvc_device_handle_t *devh) {
    UVC_ENTER();

    if (devh->info)
        uvc_free_device_info(devh->info);

    if (devh->status_xfer)
        libusb_free_transfer(devh->status_xfer);

    free(devh);

    UVC_EXIT_VOID();
}

/** @brief Close a device
 *
 * @ingroup device
 *
 * Ends any stream that's in progress.
 *
 * The device handle and frame structures will be invalidated.
 */
void uvc_close(uvc_device_handle_t *devh) {
    UVC_ENTER();
    uvc_context_t *ctx = devh->dev->ctx;

    if (devh->streams)
        uvc_stop_streaming(devh);

    uvc_release_if(devh, devh->info->ctrl_if.bInterfaceNumber);

    /* If we are managing the libusb context and this is the last open device,
     * then we need to cancel the handler thread. When we call libusb_close,
     * it'll cause a return from the thread's libusb_handle_events call, after
     * which the handler thread will check the flag we set and then exit. */
    if (ctx->own_usb_ctx && ctx->open_devices == devh && devh->next == NULL) {
        ctx->kill_handler_thread = 1;
        libusb_close(devh->usb_devh);
        pthread_join(ctx->handler_thread, NULL);
    } else {
        libusb_close(devh->usb_devh);
    }

    DL_DELETE(ctx->open_devices, devh);

    uvc_unref_device(devh->dev);

    uvc_free_devh(devh);

    UVC_EXIT_VOID();
}

/** @internal
 * @brief Get number of open devices
 */
size_t uvc_num_devices(uvc_context_t *ctx) {
    size_t count = 0;

    uvc_device_handle_t *devh;

    UVC_ENTER();

    DL_FOREACH(ctx->open_devices, devh) { count++; }

    UVC_EXIT((int)count);
    return count;
}

void uvc_process_control_status(uvc_device_handle_t *devh, unsigned char *data, int len) {
    enum uvc_status_class status_class;
    uint8_t originator = 0, selector = 0, event = 0;
    enum uvc_status_attribute attribute = UVC_STATUS_ATTRIBUTE_UNKNOWN;
    void *content = NULL;
    size_t content_len = 0;
    int found_entity = 0;
    struct uvc_input_terminal *input_terminal;
    struct uvc_processing_unit *processing_unit;

    UVC_ENTER();

    if (len < 5) {
        UVC_DEBUG("Short read of VideoControl status update (%d bytes)", len);
        UVC_EXIT_VOID();
        return;
    }

    originator = data[1];
    event = data[2];
    selector = data[3];

    if (originator == 0) {
        UVC_DEBUG("Unhandled update from VC interface");
        UVC_EXIT_VOID();
        return; /* @todo VideoControl virtual entity interface updates */
    }

    if (event != 0) {
        UVC_DEBUG("Unhandled VC event %d", (int)event);
        UVC_EXIT_VOID();
        return;
    }

    /* printf("bSelector: %d\n", selector); */

    DL_FOREACH(devh->info->ctrl_if.input_term_descs, input_terminal) {
        if (input_terminal->bTerminalID == originator) {
            status_class = UVC_STATUS_CLASS_CONTROL_CAMERA;
            found_entity = 1;
            break;
        }
    }

    if (!found_entity) {
        DL_FOREACH(devh->info->ctrl_if.processing_unit_descs, processing_unit) {
            if (processing_unit->bUnitID == originator) {
                status_class = UVC_STATUS_CLASS_CONTROL_PROCESSING;
                found_entity = 1;
                break;
            }
        }
    }

    if (!found_entity) {
        UVC_DEBUG("Got status update for unknown VideoControl entity %d", (int)originator);
        UVC_EXIT_VOID();
        return;
    }

    attribute = data[4];
    content = data + 5;
    content_len = len - 5;

    UVC_DEBUG("Event: class=%d, event=%d, selector=%d, attribute=%d, content_len=%zd", status_class, event, selector,
              attribute, content_len);

    if (devh->status_cb) {
        UVC_DEBUG("Running user-supplied status callback");
        devh->status_cb(status_class, event, selector, attribute, content, content_len, devh->status_user_ptr);
    }

    UVC_EXIT_VOID();
}

void uvc_process_streaming_status(uvc_device_handle_t *devh, unsigned char *data, int len) {

    UVC_ENTER();

    if (len < 3) {
        UVC_DEBUG("Invalid streaming status event received.\n");
        UVC_EXIT_VOID();
        return;
    }

    if (data[2] == 0) {
        if (len < 4) {
            UVC_DEBUG("Short read of status update (%d bytes)", len);
            UVC_EXIT_VOID();
            return;
        }
        UVC_DEBUG("Button (intf %u) %s len %d\n", data[1], data[3] ? "pressed" : "released", len);

        if (devh->button_cb) {
            UVC_DEBUG("Running user-supplied button callback");
            devh->button_cb(data[1], data[3], devh->button_user_ptr);
        }
    } else {
        UVC_DEBUG("Stream %u error event %02x %02x len %d.\n", data[1], data[2], data[3], len);
    }

    UVC_EXIT_VOID();
}

void uvc_process_status_xfer(uvc_device_handle_t *devh, struct libusb_transfer *transfer) {

    UVC_ENTER();

    /* printf("Got transfer of aLen = %d\n", transfer->actual_length); */

    if (transfer->actual_length > 0) {
        switch (transfer->buffer[0] & 0x0f) {
        case 1: /* VideoControl interface */
            uvc_process_control_status(devh, transfer->buffer, transfer->actual_length);
            break;
        case 2: /* VideoStreaming interface */
            uvc_process_streaming_status(devh, transfer->buffer, transfer->actual_length);
            break;
        }
    }

    UVC_EXIT_VOID();
}

/** @internal
 * @brief Process asynchronous status updates from the device.
 */
void LIBUSB_CALL _uvc_status_callback(struct libusb_transfer *transfer) {
    UVC_ENTER();

    uvc_device_handle_t *devh = (uvc_device_handle_t *)transfer->user_data;

    switch (transfer->status) {
    case LIBUSB_TRANSFER_ERROR:
    case LIBUSB_TRANSFER_CANCELLED:
    case LIBUSB_TRANSFER_NO_DEVICE:
        UVC_DEBUG("not processing/resubmitting, status = %d", transfer->status);
        UVC_EXIT_VOID();
        return;
    case LIBUSB_TRANSFER_COMPLETED:
        uvc_process_status_xfer(devh, transfer);
        break;
    case LIBUSB_TRANSFER_TIMED_OUT:
    case LIBUSB_TRANSFER_STALL:
    case LIBUSB_TRANSFER_OVERFLOW:
        UVC_DEBUG("retrying transfer, status = %d", transfer->status);
        break;
    }

#ifdef UVC_DEBUGGING
    uvc_error_t ret =
#endif
        libusb_submit_transfer(transfer);
    UVC_DEBUG("libusb_submit_transfer() = %d", ret);

    UVC_EXIT_VOID();
}

/** @brief Set a callback function to receive status updates
 *
 * @ingroup device
 */
void uvc_set_status_callback(uvc_device_handle_t *devh, uvc_status_callback_t cb, void *user_ptr) {
    UVC_ENTER();

    devh->status_cb = cb;
    devh->status_user_ptr = user_ptr;

    UVC_EXIT_VOID();
}

/** @brief Set a callback function to receive button events
 *
 * @ingroup device
 */
void uvc_set_button_callback(uvc_device_handle_t *devh, uvc_button_callback_t cb, void *user_ptr) {
    UVC_ENTER();

    devh->button_cb = cb;
    devh->button_user_ptr = user_ptr;

    UVC_EXIT_VOID();
}

/**
 * @brief Get format descriptions for the open device.
 *
 * @note Do not modify the returned structure.
 *
 * @param devh Device handle to an open UVC device
 */
const uvc_format_desc_t *uvc_get_format_descs(uvc_device_handle_t *devh) {
    return devh->info->stream_ifs->format_descs;
}

uvc_error_t uvc_get_device_with_fd(uvc_context_t *ctx, uvc_device_t **device, int fd, int busNum,
                                   int devAddress) {
    LOG_D("开始查找对应的fd的设备咯：%{public}d:::%{public}d/%{public}d", fd, busNum, devAddress);
    struct libusb_device *usb_dev = libusb_get_device_with_fd(ctx->usb_ctx, fd, busNum, devAddress);
    if (LIKELY(usb_dev)) {
        *device = malloc(sizeof(uvc_device_t));
        (*device)->ctx = ctx;//设置为当前上下文。
        (*device)->ref = 0;//初始化为 0
        (*device)->usb_dev = usb_dev;//设置为找到的 libusb_device
        //增加设备的引用计数，确保其不会被释放
        uvc_ref_device(*device);
        return UVC_SUCCESS;
    } else {
        LOG_E("没有找到设备哦");
        *device = NULL;
        return UVC_ERROR_NO_DEVICE;
    }
}